Interchanges in Pennsylvania - Mid-County Interchange

The Mid-County Interchange is the largest interchange of the Pennsylvania Turnpike. It connects Interstate 276, Interstate 476, West Germantown Pike and Plymouth Road near Plymouth Meeting, Pennsylvania. I-276 is the main, east-west, portion of the Pennsylvania Turnpike and I-476, north of the interchange, is the Turnpike's Northeast Extension. The toll free portion of I-476, south of the Interchange, is known locally as the Blue Route or Mid-County Expressway. The interchange connects I-276, I-476, West Germantown Pike, Plymouth Road in a series of ramps, overpasses and toll booths. The original, smaller toll plaza handles traffic between I-276 and the two local roads, and the newer, larger toll plaza handles the through traffic on I-476. Traffic north bound from the Blue Route has ramps to both local roads, while traffic south bound from the Northeast Extension must exit onto I-276 west, before exiting through the old toll booth to connect to the local roads.

Prior to the December, 1992 completion of the Blue Route, this area had two discrete trumpet interchanges. There was the Norristown exit off I-276 that went through a toll plaza and connected to West Germantown Pike only. The other, independent, interchange connected the terminus of the Northeast Extension, then Pennsylvania Route 9, to I-276.

In 1979 the portion of the Blue Route that would connect Interstate 76 near Conshohocken, Pennsylvania to what would become the Mid-County Interchange was opened, but it stopped about a mile short of the Interchange at Chemical Road, which intersected Germantown Pike south of its Turnpike interchange. This caused predictable problems with rush hour traffic. After the Blue Route south of I-76 was completed to Interstate 95 in 1991, the problem was worse.

Finally on 16 December 1992, the new Mid-County Interchange opened to traffic.